90 ANNUAL OF SCIENTIFIC DISCOVERY. 



amount of work in a short time, are apparent. It should be observed, 

 that although it is no part of the plan that the clay used in the 

 machine should be at all wet, yet the pulverization of the lumps of the 

 material in the first part of the process brings out a slight degree of 

 moisture, so that the powder which is subjected to pressure is slightly 

 damp ; and this doubtless adds somewhat to the tenacity and firmness 

 of the bricks. This dampness, however, does not exceed that which 

 is usual in bricks when they are considered dry. enough to be placed 

 in the kilns. 



The hammer or ram which descends upon the clay in*the moulds 

 weighs about four thousand pounds. The mechanical force which is 

 brought to bear upon each brick is estimated at one hundred pounds. 

 The whole weight of the machine, including the pulverizer and 

 screens, exceeds twenty tons. The cost is $3,200. 



. The bricks, when burnt, are found to have shrunk less than those 

 made in the ordinary way, probably on account of their greater den- 

 sity ; and, for the same reason, they retain their smoothness of surface 

 and accuracy of form. On breaking one, its compactness and sound- 

 ness are immediately obvious. As they thus can absorb but little 

 moisture, they are capable of standing the frost of the severest climate 

 without injury. An experiment in a crushing machine, by the super- 

 intendant of the Capitol at Washington, showed the strength of the 

 bricks to be sixteen thousand six hundred pounds to the square inch. 

 At the same time it was found that, by the absorption of one of the 

 bricks and the atmospheric evaporation together, during fourteen 

 hours, there was consumed less than half a gill out of a gallon of 

 water. 



The actual use of the bricks, so far as we have heard, justifies all 

 the expectations which would be formed from a knowledge of the 

 process of their manufacture, and shows that they are in no respect 

 inferior to those made in the ordinary way. Indeed, they are unques- 

 tionably better. We are told that they have been used in buildings 

 with entire satisfaction, and that some of them exposed during the 

 last winter, in sidewalks in Boston, remain as perfect as when they 

 were laid. The best quality of bricks can be made by these machines 

 at a less expense than the coarse common bricks made by the ordinary 

 processes. 



The present invention is so different, both in principle and opera- 

 tion, from all former machines, and is so perfect in theory, simple in 

 construction, and successful in its results, that we can hardly doubt 

 that its use will eventually entirely supersede that of all other 

 processes. 



We derive the foregoing facts from the Boston " To-Day." - Editor. 



A CIRCULAR SAW RUN WITHOUT AX ARBOR. 



AN invention has recently been made by Mr. A. C. George, of New 

 Hampshire, by which a circular saw can be run without an arbor, in 

 such a manner as to cut a board nearly the width of the saAv. The 



